Businessmen are being given a secret MI5 handbook to help them avoid being caught in "honeytraps" when working in Russia or China.

Some of the UK's biggest firms have received the booklet, which warns that getting drunk, gambling or womanising could see them targeted amid talk of a new Cold War.

It warns against "risky business" and lists "inappropriate activities" which even if they are not illegal can "have a lasting impact on you personally".

Published by the Centre for the Protection of National Infra­structure, which reports directly to MI5, the Smart Traveller booklet says substance abuse, excessive drinking, gambling, changing money on the black market, "flirtatious liaisons" and online dating could leave staff open to blackmail.

John Simpson, the BBC journalist, has revealed that he was targeted by a glamorous Czech spy during the Cold War, whilst Anna Chapman, the Russian spy, was married to a British man and said to have been on the brink of seducing a US congressman before her arrest.

Distributed to companies that do a lot of work overseas, particularly in Russia of China, the booklet warns that if they have sensitive assets, firms are "more at risk of espionage, intellectual property theft and a range of other threats".

Tips for avoiding falling victim to espionage include keeping electronic items in hand luggage so that they cannot be tampered with, turning off location services, avoiding public wifi and not posting updates about your location on social media. Whilst abroad, the booklet advises that travellers should try not to look "like a lost tourist".